Final answer:
The question is related to the decay rate of a radioactive material, the fraction of decays detected by a Geiger counter, and reasons for detecting only some emissions. Using the exponential decay formula, the student calculates the remaining activity after a given time and explores factors affecting detection efficiency in radiation measurement.
Step-by-step explanation:
The student is asking about the decay rate of a radioactive material. Specifically, they want to know what fraction of the decays are observed by a Geiger counter after 120 days and the potential reasons why only some decays are detected. The radioactive decay formula, which shows exponential decay, is used to calculate the activity remaining after a certain time period. In the context of the question, using an initial activity of 1.00 μCi for a Polonium-210 (Po) source, we estimate how that activity decreases over time and why not all decays are registered by the detector.
Some reasons that only a fraction of decays are observed by a Geiger counter include the efficiency of the detector, geometrical factors, self-absorption of radiation within the source, and the presence of other materials between the source and the detector that can attenuate the radiation.